Chapter 1: Driving The Roads

Section 1:

Learning Objectives:

• Measure reaction time using one of two different methods.
• Compare the different methods of measuring reaction time.
• Compare the reaction times of your classmates.
• Investigate how distractions affect reaction time.

What do you see?

I see a car crash with one yellow car on top of another orange car. A third blue car looks like it is about to crash into the other two cars as well. The third blue car looks like it is speeding. It also looks like the orange car is either leaking water or oil. Blue car is coming from a turn.

What do you think?

When a driver sees a hazard on the road they need time to overcome the nervousness and fear of getting into an accident. If you act right away your chances are better rather than if you act a split second later you chances could be worse. Distractions, visibilities, energy/how focused you are, distance, speed, and car conditions.

Investigate 1.1

Stop Watches:
2:37/2:50 13 seconds
2:03/2:25 12 seconds
2:16/2:30 14 seconds
Average: 13 seconds

Yard Stick:
14=.17
9=.13
9=.13
Average: .143

Comparisons:
1.
A.) They were not the same, but they were very similar. They were not the same because every single person has their own reaction time to things, everyone is different.
B.) The stop watch because as soon as you see your partner stop, you stop right away as well.
2.
A.) Method B: .12 Fast, .17 slow, and .14 average
B.) Yes, but they wont be too different because people who are the same age will have a similar reaction time.


Red/Green Distraction:
1: 24
2: Green
3: 17
4: 22
5: Green

Re/Green distraction with calculator:
1: Green
2: 37
3: 25

10 distractions while driving:
1: talking on the phone
2: texting
3: changing radio
4: eating
5: putting on make-up
6: being tired
7: sneezing/coughing
8: fixing hair
9: looking at the time
10: GPS

Cell Phones vs. Drunk Driving:

The Mythbusters tested if driving while talking on a cell phone is worse than driving drunk. They made a road test and they drove it first normally (controlled test) and they both passed the test. Next they drove they drove the road test while talking on the cell phone. While on the phone they were asked to repeat a sentence, answer a couple questions, then they had to list five things. They both failed the test by more than 50%. After that they took the road test drunk. They first drank a couple of beers to get to the legal limit of .075. They drank one beer and every 15 minutes they had to take a breathalyzer to make sure they were at the legal limit and not any higher than that. They took the road test and both failed by 50%. But they had a worse score while driving with a cell phone than when driving drunk. I think that driving while talking on a cell phone is a greater hazard because you have a weakened reaction time because you are distracted. Talking on a cell phone is a huge distraction, it can be hard to focus on the road and focusing on your conversation.

Physics talk:

Reaction time and distractions:

• Reaction time is the time taken to respond to a situation.
• While driving reaction time could be life or death.
• Reaction time is fast when your not distracted but while you are distracted your reaction time is slower
• Reaction time can increase or decreases chanced of a collision
• While driving reaction time is slower than during the tests we did in class.

Other factors affecting reaction time:

• Every state in America has a law prohibiting driving while under the influence of alcohol and drugs.
• Drugs and alcohol can slow your reaction time down by a lot.
• age, gender, practice, fatigue, exercise, attentiveness, and even personality are factors that can increase reaction time.

Checking Up:

1.) distraction affect reaction time because when you are or doing something else while you should be paying attention to the road that second or two it takes to look up slows down your reaction time
2.) Driving under the influence of alcohol or drugs in illegal because it can significantly slow down someone reaction time.
3.) looking down at phone, changing the radio, reading a sign on the road.

Physics Plus:

1.)

Time (s)	Distance (m)
0.00	0
0.02	.196
0.04	.784
0.06	1.764

2.) This chart and the chart from the lab are both curved upward, so they look very similar.
3.)

• Thumb and index finger right hand: 5 cm.
• Thumb and index finger left hand: 8 cm.
• Thumb and middle finger right hand: 8 cm

S1 Notes:

Essential Questions:

What does it mean?
Reaction time is the time taken to respond to a situation
How do you know?
In this section we measured reaction time by dropping rulers and seeing how far up the ruler we would catch it at, and we also used stopwatches to calculate the difference in time. Everyone has their own reaction times so the students in my class all had different reaction time but mostly they were fairly close.
Why should you care?
Reaction time is very important to driving safely. If you are distracted for a split second you can endanger yourself. Accidents are avoidable if you pay attention and have a good reaction time.

Section 2:

Learning objectives:

• Calibrate the length of a stride
• Measure a distance by pacing it off and by using a meter stick
• identify sources of error in measurements
• Evaluate estimates of measurements as reasonable or unreasonable

What do you see?

There is a tape measure laid across the floor of a hallway. One boy is taking measurements in a notebook. As another boy and a girl pasts the tape measure he will record that. the little girls strides are a lot smaller than the older boys stride

What do you think?

The first two students made a mistake because there is too big of a difference between 3 and 10. Btu the second two students did not make a mistake because they are only .01 off.
Precision-how repeatable the measurements are.
Accuracy- how close the measurement is to the true value

Investigate 1.2:

Number of strides: 37
Length of Stride: 44
Total: 1,628

Group	Stride	Meter Sticks	Tape Measures
1	2006	2253	2261
2	1100	1369	1370
3	900	1369	1370
4	867	1369	1370
5	1598	2253	2261
6	759	1370	1372

5A.) No. The results vary from 867cm to 2006cm
5B.) No because everyone has different steps depending on their height and how big of steps they take.
5C.) Everyone takes the same length steps and if everyone does this then we will have closer measurements and the results wont be that scattered.
7A.) All the measurements do not agree because they vary from 1369cm to 2253cm.
7B.) They do not agree because two of the measurements are different lenghts.
7C.) Everyone has to measure it from the same spot and not have two different lengths.
7D.) If they were given a very long tape measure, each group probably wouldn't get the same value. because the tape measure is very long its harder to keep it still and get exact measurements.
7E.) No because everyone measures things differently.
8A.) No we didn't have any systematic problems.
8B.) We didn't have any errors.

Physics Talk:

Random Errors: There is no exact measurements. In the investigate any tool you used to measure, each groups measurements still varied. Random errors are errors that can not be corrected by calculating. When you measure something it could be off by .01cm so to help decrease the chance of error you can use a more precise ruler.The uncertainty can never completely be eliminated.A meter stick that has only the centimeters noted it has a higher uncertainty than a meter stick that has millimeters noted on it. Cannot be corrected. There will always be some amount of random error that you cannot fix
Systematic Errors: If you mistake a yard stick for a meter stick and you record 4m when it really is 4yd, then you answer is a systematic error. These errors can be avoided or even corrected by calculating. Can be corrected
Accuracy and Precision: You can have precision by using a dart board and by having all the dart miss the middle but they all land in the same area. You have accuracy by having all the darts land on bulls-eye or around bulls-eye. Measurements can also vary with accuracy and/or precision. As you increase the need for precision, the measurement becomes more difficult. Four options: both, just accuracy, just precision, or neither(scattered).
SI System: In this section we will be using these following measurements: length-meter, mass-kilogram, time-second, temperature-kelvin, current-ampere

Checking Up:

1.) The difference between systematic and random errors is that systematic errors can be corrected and random errors cannot be corrected.
2.) There will always be uncertainty in measurement because not everyone has the same need for precision. There is always a gray area in measurement.
3.) The positions of the arrows on a target would be to be scattered around for it to illustrate that they are neither accurate or precise.

Do Now 9/22:

1.) 6.789, 6.784, 6.781- Random error
2.) Using inches to measure a length instead of centimeters- Systematic error

S.2 Notes:

26.7 cm +- 0.1 cm: .7 is the uncertainty
+- : "give or take"
5,000 cm +- 1,000cm
510 cm +- 10cm
10.250 cm +- .001cm
7.34 cm +- .01cm
If the measurements have no decimal the uncertainty is to the closest non zero unit to the left of the decimal.

Physics Plus:

1.) If a pool measures 50m the level of uncertainly for +-10cm would be 49.90-50.10, the level of uncertainty for 1cm would be 49.99-50.01, and the level of uncertainty for 1mm would be 49.999-50.001.
2.)24.9-25.1=.02s different between a 49.99m pool and a 50.01m pool.
3.) 50m divided by 25s = 2m/s = 200cm/s 2cm divided by 200cm/s = 1/100 = .01s (s=d/t) (t=d/s)
4.) This person can actually be slower than the previous record holder because if the previous record holder swam in a 50m pool and the new record holder swam in a 49.99m pool that is a difference that can save you extra seconds, that .01 difference means a lot.
1500m/15min=.60m/x 9/1500=1500x/1500 x=.006min x=.36s

What do you think now?:

1.) Yes, one of the students has made a mistake, and it was probably a random error.
2.) No, one of the students has not made a mistake because the answers are very close (+-.01) Measurements can never be exact.

Essential Questions:

What does it mean?:
This would be a systematic error because you can correct the mistake by calculating. A random error would affect precision and accuracy.
How do you know?:
You know that the jeweler cannot be sure that it is exactly one oz, because measurements are never exact depending on what you are using answer will always be off by a little and never be exact.
Why do you believe?:
While you are doing an experiment you can trust your measurements even though they all have uncertainty, because if you use the same tool to measure, your result will be constant and wont have too many errors.
Why should you care?:
By not estimating you stopping distance correctly while driving a car, your chances for getting into an accident increases.

Physics to Go:

5.) The measurements on the labels vary, but they are usually +-.1
6.) a. Yes this is reasonably because 1L of soda serves 6 so 2L of soda would be enough for 12 people at a meeting
b. No because, there are other factors that could change this like how fast the car is going, and how much traffic there is.
7.) No because you room's measurement is way smaller than the distance from school to your home. therefor off by 1m in your room is not equivalent to being off by 1m in measuring your home to school.
8.) a. You should drive +-5, so 55-60mph would be the best bet.

Section 3:

Learning objectives:

• Define and contrast average speed and instantaneous speed.
• Use strobe photos, graphs, and an equation to describe speed
• Use a motion detector to measure speed
• Contrast graphs of your motion
• Interpret distance-time .
• Calculate speed, distance, and time using the equation for average speed.

What do you see?:

All of the cars are in motion, you can tell by the hair blowing, and the smoke coming out of the cars. The yellow red and blue car look like their getting into a car accident. The yellow car in the back of the crash looks like its going the fastest. Yellow car was speeding and it hit the red car in the bumper pushing the red car into the blue car. On back two cars there is a good separation distance, and the three cars in the crash did not.

What do you think?:

• The safe following distance between your automobile and the vehicle in front of you should be a any distance depending on your speed, reaction time, and when you press your brakes.
• You decide what a safe following distance is by knowing how fast your going and you want to be far away enough to see the person in front of you stop so you can react to it.

Investigate 1.3:

1.)


a.)
b.) 30 mph cars were closer than the 45 mph cars. 45 mph cars were more spread out.
c.) You decide how far apart to place to the 60 mph cars by comparing it to the 45 mph cars and make the space between them bigger.
3.)

a.) C is traveling the slowest, A is traveling the fastest. I made my choice because of the distance between the cars the further away the faster it is going.
b.) Yes each automobile is traveling at a constant speed because the distance is the same between each car in each section.
4e.) The first graph was walking away from the motion sensor and over 3 seconds, it went from about 2.2 to .1. The second one while walking towards the motion sensor was also 3 seconds, and started at .1 and ended up at 2.2. The third graph was walking away from it at a normal speed then walking back very slowly which was like 11.4 seconds, and started at .1 then went to 3 then ended at .8. The fourth graph walking in both directions really fast was about 4.2 seconds, and started at .1 then went to 2.2, and back down to 6.
5a)


5b.) My prediction was not that close. The graph should have slopped up gradually.
6b.) You can determine because the first line would be the slower walking away because its a longer line and the dots are closer together, the second line would be the faster walking because its the short line and the dots are farther apart
7a.) Distance is 2.2 meters.
7b.) It took 4.9 seconds
7c.) 22 divided by 4.9 is .4489
7d.) If it went for 9.8 seconds it would be 4.4 meters. We assume that the speed was constant.
8a.) The person travels 120 ft. because it was 60f/s and his reaction time was .5s
8b.) It will be 60 divided by 1.5 which equals 40 ft.
8c.) 50 divided by .5 equals 100ft. and then 50 divided by 1.5 equals 33.3ft.
8d.) 70 divided by .5 equals 140ft. and then 70 divided by 1.5 equals 46.7ft.
8e.) For the driver to avoid hitting the car he should stay back at least 80ft. because 40 divided by .5 equals 80/

Physics Talk:

Understanding Motion:

• Speed is the distance traveled per unit time.
• Represented constant speed by using strobe photographs, distance-time graphs generated by a motion detector and an equation.

Model 1: Strobe Photos

• 
• When an object is moving at a slow speed, the distance between the objects is less than when the object is moving at a fast speed.
• Used to illustrate the velocity of an object by the distance between the object in each picture.

Model 2: Solving equations

• the average speed of a vehicle is the ratio of the total distance traveled to the total elapsed time
• 
  
• example: d=200 t=20 v=? 200 divided by 20 = 10 so v=10
• 
• 

Pages 41-43, & 46
Speed and Velocity:

• velocity is speed in a given direction.
• Velocity always includes both speed and direction.

Model 3:

• 
  
• Graphs are a visual way to represent data.Anytime an object moves at a constant speed, the distance-time graph is a straight line.
• the slope of the graph indicates the speed of the person.
• A slow speed has a gradual slope. A fast speed has a steep slope and no motion has a zero slope.

Speed and the Slope of a Distance-Time Graph:

• you can also use the slopes of distance-time graphs to obtain a quantitative(number) value for speed.
• The slope of a line is the rise divided by the run. slope=rise/run
• Slope = distance/time
• 
  
• Slope=average speed
• Slope is always the speed in the distance-time graph

Kilometers and Miles:

• highway signs and speed limits in the united states is given in mph and in any other country they use kilometers to measure long distances.
• A kilometer is a little less than two thirds of a mile.
• For shorter distances speed is measured in meters per second.
• 

Speed and Doppler Effect:

• As a driver you must be aware of the speed limit, most people are aware that going too fast is dangerous.
• An accident at a high speed results in much greater damage than at slower speed.
• Use equation v=d/t
• You can also get a sense of the speed of a passing vehicle by listening carefully to the sound of the engine and the tires on the road.
• Sound travels waves
  • the shorter the wavelength, the higher the pitch (frequency)
  • the longer the wavelength, the lower the pitch.
• As the race car approaches, you hear a high pitch and as the car departs, you hear a low pitch
• The change in pitch is called the effect.

Reaction Distance:

• At a given speed, the time is takes you to respond to a situation corresponds to the distance that the automobile travels.
• The distance that your automobile travels until you respond is known as the reaction distance
• A longer reaction time increases the distance you travel before you even begin to brake or turn.
• The longer your reaction time, the greater the distance the automobile moves before you begin sopping, swerving, or taking other appropriate action.

Checking Up:

1.) An average speed of a vehicle is different from instantaneous speed because the average speed is the speed that it has gone over a total period of time and instantaneous speed is the speed at that given moment.
2.) The speed and velocity of an object are different because velocity has a direction.
3.) If the distance-time graph shows a straight, inclined line it represents that there is a steady speed but you are walking away from the sensor
4.) Reaction time affects reaction distance because the longer your reaction time the greater the distance. If you have a short reaction you will have a shorter reaction distance.

Physics Plus:

Average speed is 27 mph because v=d/t v=80/3 v=27
Average speed is always total distance divided by total time
1.)
2.)

3a.) My estimation for the average speed would be about 25 miles per hour
3b.) v=d/t v=150m/8hr v=18.75 so the average speed was 18.75mi/h
4.) 40=20+x/2 80=20+x 8-=20=60 60=x so the second half of the trip was travels at 60mi/h

What do you think now?:

1.) a safe following distance between your vehicle and the vehicle in front of you is by knowing your reaction time and by being ahead of the reaction distance.
2.) You decide what a safe following distance is by knowing your individual reaction time which relies on your reaction distance, and which relies on distraction, and also knowing your speed.

Physics to go:

1a.) These cars are traveling at a constant speed
1b.) These cars are speeding up in the beginning then go at a constant speed toward the middle than slow down at the end.
2a.)
2b.)
3.) v=d/t first multiply t on both sides so d=vt d=350(20) d=7000 ft.
4a.) v=d/t v=215/4.5 v=47.78. Her average speed was 47.78mph
4b.) No because you don't have the instantaneous speed at that point.
5.)v=d/t v=5/.25 v=20 Her average speed that she should maintain in order to get to the park in 15 minutes should be 20mph
6a.) They maintain a steady speed but then stop.
6b.) They maintain a steady motion then stop then maintain a steady motion again.
6c.)They maintain a slow steady speed and then they speed up but at a steady constant speed away
6d.) The speed increases. (acceleration)
7a.)v=d/t d=vt d=55(.14) d=7.7
7b.) v=d/t d=vt d=35(.14) d=4.9 Compared to the 55mph reaction distance the 35mph reaction distance was lower.
7c.) if my reaction time was doubled.... d=vt d=55(.28) d=15.4 The reaction distance increases.
8a.) Experts can be sure that this is a safe following distance because they know what the average speed is suppose to be.
8b.) The safe following distance on an interstate highway and a rural road will not be the same because a safe following distance depends on your reaction time and the speed in which you are going.
9a.) d=vt d=70(.3) d=21
9b.) No it is not longer than the length of my classroom, it is about half the length.
10a.)d=vt d= 88(.5) d=44ft.
10b.)44 divided by 15 is 2.9 so there is enough room for about 3 cars or distances.
10c.)d=vt d=44(.5) d=22ft. There is only enough room for about 1.4 cars
10d.)d=vt d=(.5) d= There is enough room for
11.)

Essential Questions:

What does it mean?: To say a speed of a vehicle is 40 mph means that means if they maintain the speed it will take them an hour to travel 40 miles.
How do you know?: To measure a vehicle you need to take down the distance and the time. you would use the equation v=d/t
Why do you believe?: Strobe photo by drawing a car at different distances with the same distance in between them that is equivalent to 20mph. The graph by showing the constant speed of 20mph. Also with the equation by plugging the 20 in for velocity (v=d/t)
Why should you care?: The reaction distance depends on your reaction time and speed because the longer your reaction time is the longer your reaction distance is. Also, the faster your speed is the more time it will take to slow the car down which affects the reaction distance.

Section 4:

Learning Objectives:

• Measure a change in velocity(acceleration) of a cart on a ramp using a motion detector.
• Construct graphs of the motion of a cart on a ramp.
• Define acceleration using words and an equation.
• Calculate speed, distance, and time using the equation for acceleration.
• Interpret distance-time and velocity-time graphs for different types of motion.

What do you see?:

I see a red light on the traffic light. The red car is going very fast. A man and his dog are running away form the red car that almost hit them. The yellow car is stopped.

What do you think?:

Similar:
Different: A bus is longer and heavier than an average car so it takes them longer to build up to a speed and longer to slow down a speed.

Investigate 1.4:

1.) No because it goes faster as time goes one.
2.)
4= the car travels slower at the beginning and speeds up
3= the car travels faster at the beginning and slows toward the end
1= the car moves at a constant velocity away from zero
2= the car moves at a constant velocity toward zero
Run 1:



the velocity speeds up and then at 1.5 seconds it slows down and stops.
Acceleration:

Run 2



Since the car is being pushed toward the motion detector it is in a negative velocity. The velocity has an initial increase from the push and then it slows down at a constant rate
Acceleration:

Run 3:



Since the car is being pushed toward the motion detector it is in a negative velocity. There is an initial push, then it speeds up at a constant rate then slows down and stops.
Acceleration:

Run 4:



The velocity has an initial push which speeds it up then it slows down at a constant rate then stops.
Acceleration:

Run 5:



As the car is being pushed up the ramp away from the motion detector the speed has an initial speed up then slows down at a constant rate. As the car come back towards the motion detector it goes into the negative velocity and speeds up at a constant rate then comes to a stop.
Acceleration:

Run 5 in class:

Explanation why velocity is the slope of a d vs. t graph, why acceleration is the slope of a v vs. t graph, and why you need to use tangent lines to find instantaneous speed.:

1. Velocity is the slope of a d vs. t graph because slope=rise/run-distance/time=velocity
2. Acceleration is the slope of a v vs. t graph because slope=rise/run=velocity/time=acceleration
3. You need to use tangent lines to find instantaneous speed because in order to get a slope you need to get two points and by using a tangent line of one point you are able to find the other point to find the slope.

Physics Talk:

Changing Speeds
Acceleration:

• The motion of a falling object is a common example of something changing speed.
• Galileo was the first person to apply math to the study of a change in the speed of a falling object.
• He used a water. water flows through a funnel into a bowl, the more time that elapses, the more water is collected
• He though that a ball rolling down an incline was like watching a falling object in "slow motion
• Galileo found that if he looked at the change in speed with respect to the change in time, the value remained the same as the ball descend the ramp
• the velocity of the cart changed at a regular rate and is represented by a straight line on the velocity vs. time graph

Acceleration is a vector Quantity:

• Acceleration means "how fast the velocity changes."
• Velocity means "how fast an object is going (speed) and in what direction"
  • Velocity therefor is a vector quantity
• A vector quantity is a quantity has both magnitude (size) and direction
• An automobile can produce velocity changes in less time than a bus. Automobile can exhibit greater acceleration
• The distinction between speed and velocity become important when changes in direction can occur.
• Ways to change your automobile's velocity
  • to speed up (increasing the speed, or magnitude of velocity)
  • to slow down (decreasing the speed, or magnitude of velocity)
  • turn (change direction of velocity)
• Velocity changes as time elapses.
• The vocabulary used to describe a change in velocity with respect to time is positive acceleration and negative acceleration
  • Positive acceleration means that velocity of the object is increasing overtime
  • Negative acceleration means that the velocity of the object is decreasing over time, if the object is moving in a straight line

Describing Accelerated Motion Using Strobe Photos:

• Because the speed is always changing during constant acceleration, the strobe illustration below shows the automobiles moving greater distances during each second of travel.

Describing Acceleration Using an Equation:

• Acceleration = change in velocity/ change in time

Using the Equation for Acceleration to Find Other Quantities

• 

Sample Problem:

• 

Describing Acceleration Using Graphs:

• If distance is represented on the y-axis and the time is represented on the x-axis, then the graph showing constant acceleration is a curve
• The slope of the tangent line to the curve at any point gives the instantaneous speed at that point
• an increasing speed during a time interval is an acceleration
• If the velocity is represented on the y-axis and the time is represented on the x-axis, then the slop of the graph will b equal to the change in velocity with respect to time.
• the acceleration is equal to the value of the slope of the velocity-time graph

Describing Types of Motion Using Graphs:

• You can determine the general motion of an automobile by reviewing the distance vs. time graph, the corresponding velocity vs. time graph, and the corresponding acceleration vs. time graph

Checking Up:

1.) Acceleration is change in velocity divided by the change in time. delta a = delta v/ delta t
2.) Meters per second squared.
3.) The difference between a vector and a scalar quantity is that a vector involves both direction and size while a scalar quantity has size but not direction
4.)

5.) The slope of a velocity-time graph represents acceleration.

Physics Plus:

Kinematics Problems:

Section 5:

Learning Objectives:

• Plan and carry out an experiment to relate braking distance to initial speed
• Determine braking distance
• Examine accelerated motion

What Do You See?:

• The car is going really fast, you know that because of the smoke coming from the tires and the things blowing in the wind from the car.
• The car is trying to brake so that it does not hit the moose.
• The car is jerked forward because it is going from a fast speed to a stopping.

What Do You Think?:

• You must consider your speed
• Your reaction time
• And your braking distance.

Investigate 1.5:

1
A) Prediction of what the graph will look like:

B) My prediction of the graph was drawn this way because i thought that the car would continue at the same speed and then eventually slow down.
4.

Run	Measurement
1	3.2m
2	3m
3	3.5m
4	2.8m
5	2.6m
6	1.5m
7	2.5m

Slopes for graphs:
2) 1.75
3) 2
4) 1.2
5) 2.2
6) .75
7) 2
Slope for run 4:

Slope for run 5:


5.
A)
B) A car with faster initial speed will have a longer braking distance because it is going faster and will take longer to slow down.
C) Around the same
D) Most of the other groups have curvy looking graphs.
E) After viewing other groups graphs i feel that ours are almost close to what they should have looked like.

6. For the 6th run the slope was .75 and almost double .75 is 1.75 which was from run 2.
A) Doubling the speed affects the breaking distance because it will make the car have a longer breaking distance because it is going significantly faster.

7. For the 6th run the slope was .75. Double that speed is 2.25. The closest number that was had to that was 2 on run 3 and run 7.
A) Tripling the speed would make it even harder for the car to stop making the breaking distance even longer than doubling it.
B) The breaking distance would be 4 times longer if we made the speed 4 times faster.

Physics Talk:

Checking Up:

1. If a vehicle is traveling at a constant velocity and then comes to a sudden stop it has a negative acceleration. It is a negative acceleration because the car has stopped.
2. If a car is traveling at a fast speed then it will take the car a longer time to brake because the speed slowly will become slower
3. The term negative acceleration is used instead of deceleration because it is referring to the speed rather than the direction of the car.

Notes 11/2/11:

Notes 11/3/11:

Section 6:

Learning Objectives:

• Investigate the factors that affect the STOP and GO Zones at intersections with traffic lights
• Investigate the factors that result in an Overlap Zone or a Dilemma Zone at intersections with traffic lights
• Use a computer simulation to mathematically model the situations that can occur at an intersection with traffic lights

What Do You See?:

• The green car is speeding an is going through the red light
• The red car was speeding but it coming to a stop because of the red light
• The red car tried to slow down because a cop is there watching them

What Do You Think?:

1. If all traffic lights stayed yellow the same amount of time, it would affect drivers' decisions at intersections becasue everyone's counting could be different. By other peoples speeds needing different stopping distances.
2. An intersection with a traffic light can be dangerous because of the different decisions of people, if someone is behind you and wants to go and you don't go then you can get rear ended. Its all about judgement.

Investigate 1.6:

Part A:
3a.) Yes car B will be able to make it through
3b.) Yes car B is in the Go zone becasue the car A behind it says that it is in the Go zone.
3c.) Yes any car closer to the intersection than car A is in the Go zone.
3d.) Car C is in the Stop zone not the Go zone. If it continues to go through it risks its chances into getting into a car accident.
4a.) Yes car E is in the Stop zone because it is behind Car D.
4b.) Car F is not in the Stop zone, it is in the Go zone.
4c.)

5a,)
5b.)
5c.) ty - increases the go zone, tr - increases the go zone, v - increases the go zone, a - shortens the go zone, w - shortens the go zone
6a.) 53 meters
6b.) 63 meters
6c.) yes, because the go zone would be longer
6d.)

7a.) Yes it changes the go zone or stop zone by increasing or decreasing on the change in variable
7b.) By increasing the yellow-light time the go zone increased and when you decrease the number the go zone decreased
7c.) Go Zone is found by multiplying the speed of a chicle and the yellow light time then subtracting the width of intersection.
7d.) These factors will affect the amount of time you have to get through a yellow light and decide if you can make the light
7e.) These factors do not appear and do not affect the Go zone because you would not be slowing down (negative acceleration rate) and you are not responding to change anything (human response time)
8.) Speed of vehicle, human response time, and negative acceleration rate
8c.) Yes becasue i understand the concept of why the speed, response time, and negative acceleration rate affect the stop zone
9a.)
vehicle speed multiplied by response time plus vehicle speed squared divided by two multiplied by the negative acceleration
Stop Zone= (B5*B4) + (B5^2) / (2*B6)
SZ= (vtr) + V^2 / 2a
^reaction distance
^breaking distance
9b.) They are not in the equation because they do not affect the size of the stop zone.
Part B:
1.) Car A and Car D i would stop because you are in the stop zone, but Car C and Car B i would go because you are in the go zone.
2.) Car E and Car F i would stop because you are in the stop zone. Car G i would go because you are in the go zone. Car H i would go because you are in the overlap zone so you can either go or stop driver choice.
3.) Car J and Car L i would stop becasue you are in the stop zone. Car K i would go becasue you are in the go zone. Car M i would go, but it is drivers choice becasue you are in the dilemma zone it could be either stop or go.
4a.) Intersection I has both a go and stop zone right after another, Intersection II has a go and stop zone with an overlapping zone, and Intersection III has a go and stop zone but with a dilemma zone.
4b.) Your choices would be to either stop or go. In the overlapping zone either stopping or going would be okay. It is up to the drivers choice.
4c.) Your choices would be to either stop or go. In the dilemma zone it is hazardous both way but it is up to the drivers choice to either stop or go.It is a risk both ways.
4d.) Intersection II has an overlap zone and Intersection III has a dilemma zone.
5a.) If after subtracting the go zone from the stop zone and you get a negative number, the intersection will become unsafe.
5b.) Overlap zone.
5c.) Now a dilemma zone.
5d.) Yes, it is now an overlap zone.
6a.) Longer it is an overlap and shorter it is a dilemma.
7a.) Yes, negatively moving the numbers down makes the change in dilemma for prominent.
8a.)
9a.)

Physics Talk:

• Mathematical models- formulas or equations that are used to help us understand something that is in the real world BUT they don't need to actually relate to real objects
• Yellow Light Model- 5 variables: velocity, reaction time, yellow light time, width of intersection, negative acceleration
  • different variable to determine whether to stop or go through a yellow light
    • 1.) determine the SZ and the GZ
    • 2.) determine safety- DZ or OZ
• Go Zone- includes all positions where you can safely go through a yellow light at an intersection
  • 3 variables impact the GZ
    • 1.) velocity of car (v)- if velocity increases, the GZ increases
    • 2.) yellow light time (ty) - if yellow light time increases, the GZ increases
    • 3.) width of the intersection (w)- if width increases, the GZ decreases
  • Equation to find GZ
    • GZ = vty - w
• Stop Zone- all the positions where you can safely stop at a yellow light
  • 3 variables that impact the SZ
    • 1.) velocity (v) - if velocity increases , then SZ increases
    • 2.) reaction time (tr)- if reaction time increases, then SZ increases
    • 3.) negative acceleration (a)- if negative acceleration increases, then SZ decreases
  • Equation to find SZ
    • SZ = vtr + v^2 / 2a
• Dilemma vs. Overlap Zones- zones that help determine the safety of the intersection
  • Dilemma Zone- the intersection is not safe
    • Creates an area where stopping and driving is not safe
• Overlap Zone- the intersection is safe
  • Creates an area where stopping or driving are both safe
• Limitations Of The Yellow Light Model
  • Input values for speed of vehicle, width of intersection, and yellow light time
  • Output values for Go Zone and Stop Zone
  • Positions where you can safely stop at a yellow light
  • Doesn't take length of the vehicle into account.

Checking Up 1-5:

1. The spreadsheet is a model because it uses formulas and equations to help understand what it is in real life.
2. The Go Zone is the the distances where you can go safely through a yellow light
3. The Stop Zone is the distances where it is unsafe to go through a yellow light.
4. The Overlap Zone is the area where stopping and driving is both safe.
5. The Dilemma Zone is the are where stopping and driving are both unsafe.

Physics Plus 1-7:

1.)The speed of the vehicle will affect the Go Zone by making it longer becasue you can cover more distance in less time, and also making the Stop Zone longer because there is more room to come to a stop.
2.)


3.)

4.)

5.)The overlap Zone is on the first chart(#2) and the Dilemma Zone is on the second chart(#3).
6.) Then driving at a low speed, it will take the car less time to stop so the Stop Zone will decrease.
7.) Yes accelerating can help you get through a light but your chances of getting into an accident will increase. If you drive at fast speeds and are not in the Go Zone when there is a red light you will risk getting into an accident.

What Do You Think Now?:

1. If all traffic lights stayed yellow at the same time, it would affect drivers decisions at intersections because they would know the time it would take to get through the yellow light and the drivers would speed up to make it through knowing the time.
2. An intersections with a traffic light could be dangerous if you are in a dilemma zone becasue either stopping or going will be dangerous.

Essential Questions:

1.) Go Zone- width of intersection, velocity of car, yellow light time
Stop Zone- velocity, reaction time, negative acceleration
Dilemma Zone- distance from intersection, and velocity of car
2.) To understand the Go, Stop, Overlap, and dilemma zone by looking at my spread sheet you need to know the go zone and stop zone equations. Go Zone=(speed*yellow light) - width, Stop Zone=(speed*response time)+(speed^2)/(2*negative acceleration rate), and the overlap and dilemma zone is found by subtracting the go and stop zone.
3.) These models allow you to test what will happen at different speeds, times, and distances.
4.) Understanding the physics of the go, stop, overlap, and dilemma zone can help improve your driving and make you more aware because now when you come to an intersection with a yellow light you will know whether to stop or go through.

Physics To Go 1-8:

1a.) The Go Zone
GO Zone=(velocity*yellow light time) - width of intersection
Go Zone = 24m
1b.) The Stop Zone
Stop Zone= (velocity*reaction time) + velocity^2/(2*negative acceleration)
Stop Zone= 37.5m
1c.)
2a.) The Go Zone
Go Zone=(velocity*yellow light time) - width of intersection
Go Zone= 105 meters
The Stop Zone
Stop Zone=(velocity*reaction time) + velocity^2/(2*negative acceleration)
Stop Zone= 120 meters
2b.) The Go Zone
Go Zone=(velocity*yellow light time) - width of intersection
Go Zone= 65 meters
The Stop Zone
Stop Zone=(velocity*reaction time) + velocity^2/(2*negative acceleration)
Stop Zone= 60 meters
Go Zone is larger than Stop Zone.
2c.)
3.) The increase in stop zone will not effect the go zone becasue it is not a part of the equation to find to find the go zone, but since it is in the equation for the stop zone it will effect the stop zone.
4.) Worn tires and bad brakes will make the driver know when they need to stop before they get to the light. They will need more time to brake when they get to the light becasue their brakes are not good. The stopping zone will become effected becasue worn tires will make you need to stop earlier.
5.) Delayed green is for when drivers go through yellow lights they will not get hit.
6.) Having a countdown on a stop light is very dangerous because people will try to speed through the light thinking they have enough time and speeding when there is not enough time to make it through. The stop zone will increase because the car will speed to get through and step on the brakes when they realize they can not make it through causing an accident.
7.)

Using the excel charts. A.)go zone- 48 meters, stop zone- 52.6 is unsafe. B.) go zone- 72 stop zone- 52.6 is safe. C.) go zone- 48 stop zone- 48.6 is unsafe . D.) go zone- 48 stop zone- 64.6 is unsafe. E.)go zone- 40.5 stop zone- 34.1 is safe.
8.) No painting stop and go lines at intersections would not work becasue stop and go zone are all different depending on speed of vehicle, yellow light time, response time, negative acceleration, and width of intersection. Everything is different.
For quiz:

• which variables impact which things
• use the stop zone and go zone equations- be able to find other things using them
• know how dilemma and overlap zone can be formed

Section 7

Learning Objectives:

• Recognize the need for a centripetal force when rounding a curve
• Predict the effect of an inadequate centripetal force
• Relate speed to centripetal

What Do You See? :

• The car is speeding
• When speeding around a curve you cant go fast and the car is going way to fast and is not under control.
• If the car keeps going there is probably going to be an accident
• The car is on two wheels now that it is making a really sharp turn.

What Do You Think? :

• The sign is indicating to slow down because when you go fast around the turns it is unsafe and the sharper the turn the more dangerous it is.
• The amount you should slow down is determined on how sharp the turn is.

Investigate 1.7:

1a.) From where the car stops, it will keep going straight.
2a.) The string pulls the car in a circle.
2b.) We stopped it in front of us so it continued to go forward and straight.
3a.)

4a.) 20 cm
6a.) 22. 55
6b.)
6c.)
6d.) 10 spins is more accurate because if you do it more, it is an average. If you do it only once, it will most be off and not accurate.
7.)

On Sandpaper:
4a.) 20 cm
6a.) 12. 95
8a.) The sandpaper will affect it because you'll be allowed to go faster without it falling off the turntable. Friction is caused.
9a.) If you have a bigger radius, the turn will be a bigger so it's easier to make the turn and you won't have to slow down as much. It is a gradual turn.
9d.) The maximum speed decreases as the radius decreases.

Big Washer:

Radius(cm)	Time of 1 Rev(s)	Time of 1 Rev(s)	Time of 1 Rev(s)	Average Time of 1 Rev(s)	Circumference(cm)	Maximum Safe Speed(m/s)
20	3.55	3.52	3.16	3.41	125.66	3.55
10	3.05	1.71	1.69	2.15	125.66	3.05
3	1.85	1.19	1.05	1.36	125.66	1.85

SMALLER WASHER:

Radius(cm)	Time of 1 Rev(s)	Time of 1 Rev(s)	Time of 1 Rev(s)	Average Time of Rev(s)	Circumference(cm)	Maximum Safe Speed(m/s)
20	1.27	1.98	2.03	1.76	125.66	2.03
10	2.13	1.59	1.72	1.81	125.66	2.13
3	1.18	1.38	1.10	1.22	125.66	1.38

10a.) With a heavier truck, it affects how fast it can move through a turn because the bricks make it heavier.The lighter truck would have an easier turn and the bigger car would feel the turn more.
10c.) Yes because it slows it down.

Physics Talk:

Circular Motion
Centripetal Force:

• the car required the force of the string to keep it moving in a circle
• When you let the string go, the car traveled in a straight line
• there was no longer a force keeping it moving in a circle
• Newtons law states that an object in motion will stay in motion at a constant speed and travel in a straight line unless a force acts on it
• when you observe something moving along a curved path, you should recognize that there has to be a force acting on the object
• The force of the string and the force of friction between the block and turntable is always toward the center of the circle
• when a car makes a turn, there is a force of friction between the tires and the road that keeps the automobile moving in the circle
• when you eliminate the friction, such as an icy road, the car will move in a straight line and will not be able to turn
• this force of friction is toward the center of the circular curve
• Centripetal force is a force directed toward the center to keep an object moving in a circular path
• the centripetal force can be the tension in the string, the friction between the block of wood and the surface of the turntable, or the friction between a car and the road
• Changes in velocity with respect to time are called accelerations
• A vehicle that is changing directions is also accelerating
• The acceleration associated with an automobile changing directions if referred to as centripetal acceleration
• Acceleration is the change in velocity with respect to time
• Velocity can change when an object speeds up, slows down, or changes direction

Checking Up:

1.) Center
2.) Centripetal force
3.) Centripetal force
4.) The velocity is changing.
5.) When an object is slowing down, speeding up, or changing direction
6.) Gravity

Physics Plus:

Physics To Go:

#'s 1-4 and 8



4a.) The car will have a greater risk of flipping over.
4b.) With a road that is slippery, there is little friction.
4c.) There is basically no friction so you should slow down
5.) A nascar, or a windmill
7.) The road is what contains the friction to make the car stay on the road, and this is why the road turns the car.
9.) They are both correct, just uses different wording.
11.) The are dangerous because with a slight turn they will probably be going fast. The curves will become smaller but they will still be driving too fats.
12.) ?